Altruistic behavior and motivation has traditionally been regarded as a defense mechanism defined by the vicissitudes of instinctual gratification. In this article, we suggest that there exists a substantial body of evidence from the fields of ethology, infant research, and experimental psychology to support the existence of an independently motivated altruism that is nondefensive in nature. We attempt to show how the view of altruism as a universal motivational system stems from the recent developments in evolutionary theory and contributes to (...) our understanding of intrapsychic factors influencing human behavior in general and the process of psychotherapy in particular. It is not our goal to prove the existence of "pure altruism" that can never be derived from selfish motives. Rather, our thesis is that self-oriented and altruistic motivations are equal and essential partners in human evolution and development. It is the optimal balance of these two forces that is necessary for evolutionary advancement and for psychological health. (shrink)